Bentonite clay with different nitrogen sources can effectively reduce nitrate leaching from sandy soil

Nitrate (NO3-1) leaching from soils results in the lower soil fertility, reduced crop productivity and increased water pollution. The effects of bentonite clay mixed with various nitrogen (N) fertilizers on NO3-1 leaching from sandy soils haven’t been extensively studied. Therefore, the present lysimetric study determined NO3-1 leaching from bentonite [0, 2 and 4% (m/m)] treated sandy soil under three N sources (calcium nitrate [Ca(NO3)2], ammonium chloride [NH4Cl], and urea [CO(NH2)2] at the rate of 300 kg N ha-1). Results showed that bentonite markedly reduced NO3-1 release in the leachate, while 4% bentonite retained higher NO3 in the soil. The NO3-1 leaching from sandy soil varied with N sources as Ca(NO3)2 > NH4Cl > (CO(NH2)2. At early stages of leaching, higher concentrations of NO3-1 were detected in leachate with both NH4Cl and Ca(NO3)2, but leaching of NO3-1 increased with urea at later leaching stages. The amount of total NO3-1 retained in soil was conversely related to the amount of NO3-1 in the leachate. This study indicated that soil amendment with bentonite could efficiently mitigate NO3-1 leaching from sandy soil and hence prevent N fertilizer losses and groundwater pollution.

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The data underlying the results presented in the study are available from (include the name of the third party  [ Figure 3]. Urea form of N showed consistent increases in NO3 -1 concentrations in water collected 214 in later leaching stages [ Figure 3]. This could be associated with increased nitrification process in 215 soils under unsaturated conditions [54], which might have resulted in increased NO3 -1 leaching at 216 later stages. Accumulation of NO3 -1 was more in the soil sampled from the lower layer of the 217 column after a leaching process, showing the sequence as CO(NH2)2 > NH4Cl > Ca(NO3)2.

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The amount of total NO3 -1 retained in soil was termed as nitrate loads conversely related to 219 the amount of NO3 -1 in the leachates [ Figure 4]. An enhanced application of bentonite significantly 220 retained NO3 -1 in the soil columns. leaching.

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A reduction in the NO3 -1 leaching was expected when clay material was applied to the soil.

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Reports evaluating the interactive effects of bentonite material and N sources on the reduction of 102 NO3 -1 leaching from sandy soils are scanty. Therefore, the objective of the present study was to 103 investigate the influence of bentonite on NO3 -1 leachability from a sandy soil after application of 104 three N sources.

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The amount of total NO3 -1 retained in soil was termed as nitrate loads conversely related to 219 the amount of NO3 -1 in the leachates [ Figure 4]. An enhanced application of bentonite significantly  Ca(NO3)2 as N sources could effectively mitigate NO3 -1 leaching from sandy soils.

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There is a general consensus that nitrate leaching from soils has caused substantial environmental 59 threats. The primary source of N pollution in surface and ground water is mainly related to N 60 fertilizers. Therefore, an effective technology is required to prevent NO3 -1 losses from sandy soils.

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Developing an effective technology to retain nutrients in soils is imperative to prevent NO3

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...    Higher quantity of NO3 -1 was retained in urea treated soil followed by nitrate and   conditions. However, the mobility of both N forms can be maintained by adjusting the rates of 312 Ca(NO3)2 and urea along with bentonite clay under field conditions. The study suggested that 313 bentonite amendment with Ca(NO3)2 as N sources could effectively mitigate NO3 -1 leaching from 314 sandy soils.  Am.